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# NYC Architects- Plumbing fixtures code question

sparkyy

Hi all.

I have a project in NYC within cellar levels of housing complexes. The cellar level has multiple occupancies including Factory/Industrial, Storage, Business, and sometimes Assembly. I used the 2022 NYC BC to determine the total occupant load and 2022 NYC PC to determine the plumbing fixture counts.

Since the various occupancies have such small areas, if I use the standard method of calculating fixture totals, I end up with like 8 WCs just because I'm adding fixtures that are needed for each of the occupancies. My question is- have ya'll ever used the fractional method?

Per 2022 NYCPC 403.1.1 Fixture calculations (image attached) I took my occupant load and divided up by each occupancies' required fixture ratios in 403.1. Then I add all the fractional numbers of plumbing fixtures, then round up to the next whole number to get my total fixtures.

Attaching another image showing a sample calc - in red column the calculation using the standard method vs the last column in black showing the fractional method.

Has anyone used this method?

BulgarBlogger

Is this an entirely commercial project? In other words, do you have resi above?

isoprocess

Using fractional values is the standard approach for mixed-use occupancies, precisely to manage fixture counts. The code may not specify, but the presupposition is the mixed occupancies have access to the shared fixtures -- you may want to further subdivide the calculation if you have separate tenants with limited access to certain facilities.

One question: how do you have fractional occupants? At least those numbers should be rounded up to the nearest integer before starting the plumbing fixture calculations.

sparkyy

Great, thank you. I will be going w the fractional method for the fixtures. I don't have fractional occupants, the ratios on table 403 are applied to the occupant totals from different occupancies to achieve fractional fixture numbers, which I will sum up for a total then round up to a whole number.

isoprocess

re: fractional occupants, I'm looking at the "Occupant Total" column that appears to have 1.71 B occupants and 7.74 S occupants. It shouldn't make a difference to your calculations, but it will look fishy if it's tabulated this way on a filing drawing.

sparkyy

Ah I see what you mean! Meant to round up the occupant counts. Thanks for the catch.

BulgarBlogger

yes, I’ve used this method before. It’s valid.

But there was a reason I asked about whether there is resi on upper levels. Lmk.

sparkyy

Yes, residential on upper floors. My code consultant also just confirmed that the fractional method would work. Thanks for the input!

BulgarBlogger

I'm an NYC Code expert as well. Anyway, are you aware of this Building's Bulletin? BUILDINGS BULLETIN 2012-008 - Zoning (nyc.gov)

BulgarBlogger

I'm not sure if this is ground up or not, but if it is, you might want to look into "multiple cellar levels" not exceeding 50% of the total residential floor area anywhere in the building as that may affect the feasibility of having multiple cellar levels as well as the impact that may have on the plumbing fixtures at those level(s)...

isoprocess

Is the suggestion that, depending on how those residential accessory spaces are used and sized, the accessory spaces may not contribute to the plumbing fixture calculations since they are used by the residential tenants who have their own toilet facilities in their dwelling units? E.g. a cellar amenity floor in a residential building could have zero restroom fixtures as of right .

sparkyy

@BulgarBlogger, thank you for sending that. I was not aware of that bulletin. This is a renovation project with most of the SoW at the residential portions in the upper levels. The cellars are being renovated for expansion of electrical services though there are assembly occupancies where we are providing new finishes. The cellar is only one level and is definitely less than 50% of the total residential floor area. I noted cellars plural because there are multiple buildings within the development. The cellar spaces are sometimes used by the residents (assembly spaces) but for the majority are used by the maintenance folks... I do not believe I can call them out as accessory - isn't accessory use clause typically helpful for calculating occupants via 1968 code? I am using the 2022 NYC BC

isoprocess

@sparkyy, accessory occupancy is still a thing in 2022 NYC BC, see section 508.2. I have not worked on any projects that used accessory occupancies, but my understanding is it's used to improve a building's height and area limitations and fire separations that might otherwise be required if designed as mixed-use separated or mixed-use non-separated. My read of Buildings Bulletin 2012-008 is the "accessory" here is not the same as 508.2; 508.2 defines an accessory occupancy as no more than 10% by floor area in a single story e.g. a storage closet on an otherwise all residential floor. The bulletin "accessory" references the NYC zoning resolution definition but may have crossover benefits to the building code; you should ask your code consultant whether the guidance in the bulletin has any merit towards reducing your plumbing fixture calculations, if that is desirable.

BulgarBlogger

@sparkyy Are you modifying the CofO? If so, you'll have to modify the schedule A and file an Alt 1. Alt 1's might also involve updating some zoning info/clacs.

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